Method of improving gasoline



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men or rinrnovmaaasomne llmir Epatiefl, Dhicago, llll assignor to Universal' illill'l rodncts Company, Chicago, Ill, a corporation ofEllelaware No Drawing. Application .l'ully 5,1932, Serial No.

t @laims.

This invention refers more particularlyv to the manufacture ofhydrocarbons of an aromatic or cyclic character suitable for use as highanti-- knock blending material in motor fuel, such as gasoline. a

In a more specific sense the invention relates to the more emcientutilization of the gaseous lay-products of cracking so that theyareemployed to increase the yield, the anti knocking character and thestability of cracked v'gasolines. While the process is of special valuein its application to cracking processes, its use is also of commercialadvantage in balancing the overoleflns is not always possible as thecharacter of charging oils varies with the type oi crude 'oil from whichthey are produced and when intensive cracking conditions are employed inan efiort to increase the amount of aromatics and hence the anti-knockvalue, undesirably large losses'ip gas and coke are encountered andfrequently the amount of oleflns, particularly those of a highlyunsaturated and unstable character, increases roughly in proportion tothe-increase in aromatics. As a general rule the percentage of oleflnsin the gaseous products from cracking operations also increases inproportion to the intensity of cracking conditions.

The present process comprises as one of its steps-the utilization of theolefinic content of gases from cracking operations, these'olefins beingcaused to unite with aromatic compounds so that hydrocarbons of highanti-knock value are produced. Other objects and advantages will becomeevident as the description of the invention proceeds.

In one specific embodiment the invention com- However, complete controlof the proportion of aromatics to Renewed .l'uly 25, 1935 (G11.PEG-Jill) prises subjecting gases from cracking to s peratures above 9000., under sub-atmospheric pressures for periods of time less than 0.1secondto increase the olefinic contentthereof and then causing the'olefins in the highly oleic a gas mixture to combine with aromatichydrocarbons in the presence of sulphuric acldat 'norme] orsub-atmospheric temperatures to produce aromatic hydrocarbon derivativesof high antiknock value. lo

' In a further specific embodiment, hydrocarbon gas mixtures fromcracking or other sources containing substantial percentages ofhydrocarbons of more than one carbon atom are sub ected to temperaturesin excess of 900. C. at s pheric pressures for times under 0.1 secondand the oleflns in the gas are then caused to combine with aromatichydrocarbons in the presence-of sulphuric acid, the aromatichydrocarbons being present in hydrocarbon mixtures of. appro motor fuelboiling range.

. The first step of the present process wherein unsaturated hydrocarbonssuch as acetylene, ethylene, propylene, 'butyleneo, amylenes, etc., areproduced by pyrolytic treatment of hydro- 25 carbon gas mixtures difiersfrom previously employed processes principally in the use ofsubatmospheric pressures of the order of 50 mm. of mercury absolute incontrast to atmospheric or super-atmospheric pressures and the use ofex- 30 tremely low time factors of the order of 0.01 second or lower inmost instances, the sheet of the combined reduction in pressure and timeof treatment serving, to arrest the reactions of decomposition at apoint corresponding to the in- 5 itial stage of decomposition of thehydrocarbons concerned so that subsequent condensation andrearrangements of unstable radicals into compounds of a cyclic characteris substantially prevented. Previous pyrolytic processes employed 0 uponhydrocarbon gas mixtures similar to those to which the first step of thepresent process may be applied have produced relatively low yields ofthe olefinic hydrocarbons, sometimes only a fraction of 1%while underthe customas arily'used conditions of temperature, pressure and time thebest yields of olefins seldom exceed 15 to 20%. The first step of thepresent process makes possible the production of greatly improved yieldsof oleflnlc hydrocarbons'as will -atmos- 'be shown in the examples to besubsequently given.

Table 1 contains significant data obtained in treating gases from awidely used commercial cracking process by the first step of the processof the present invention, and shows the yields of dlfierent unsaturatedhydrocarbons obtained at different temperatures and low contact times.

The original gas mixture had the following composition:

Volume percent Acetylene 0.4 Ethylene 4.6 Propylene 5A i-Butene 2.9 1.3Butadiene 1.3 Methane 26.6 Ethane" 21.1 Propane 16.3 n-Butane 1.5.i-Butane 0.8 n-Pentane 1.9 i-Pentane 1.7 Hydrogen 5.8 Carbon monoxide;0.5 Carbon dioxide 1.5 Nitrogen 4.7

The pressure employed in the runs which furnished the data given in thetable was 50 mm. of mercury absolute.

Table I Maximum liters oi hydrocarbons Temgeomtm' from 100 liters oi gasgoggggtmte maximum Propylene Ethylene Acetylene yield Consideration ofthe above data indicates that a temperature of 1100 C. produced themaximum yield of ethylene and that increasing or decreasing temperaturedecreased the yield. The

yield of propylene representing olefins of high- I.

er molecular weight than ethylene increased with decreasing temperaturewhile the yield of acetylene decreased markedly with decreasingtemperature, reaching a negligible value at 1000" C. The time factorsemployed will be seen -to be extremely small in comparison to time factors frequently employed in the pyrolytic treatment of hydrocarbon gasmixtures for the same objects. The use of the low time factorcorresponds to a high yield of desired products for a given size ofequipment.

It will be seen also that since the relative proportions of acetylene,ethylene and propylene vary with the temperature of, treatment underapproximately equivalent conditions of time factor that some control isoffered of the proportions 01' oleflns oi diflerent molecular weight anddegree of unsaturation. As will be brought out at a later point, thepossibility of such a control may sometimes be of advantage in view ofthe varying character of the aromatics with which the olefins are to becondensed in the case of particular stocks to which aromatics have 15been added from outside sources or in which aosasev aromatics orbenzenoid hydrocarbons are present as a result of the cracking of someheavier charging oil.

Another feature of the first step of the process of the inventionappears in the use of hydrocarbon gas mixtures instead of individualhydrocarloans as starting material. When employing individualhydrocarbons, such as methane or ethane for the production of ethyleneby cracking, the allowable variation in time factor if maximum yieldsare to be produced is only 0.0012

second either side of the optimum. When em- The reactions involved inthe second step of the process are essentially those between olefins andaromatics and as a typical example of this type of reaction thereactions which occur between propylene and benzol in the presence ofsulphuric acidat a temperature of approximately 0 C. may be cited. Toproduce these reactions propylene is passed into a well stirred mixtureof benzol and concentrated sulphuric acid in proper proportions, themain product being mono-iso-propyl benzol according to the followingreaction:

CaHo CeI-Ie CeHe-CaHr Propylene Benzol Mono-lso-propyl benzol There isalso produced concurrently a limited yield 01' di-iso-propyl benzolaccording to the following equation:

zcsm CsHe condemn Propylene Benzol Di-iso-propyl benzol the relativeproduction of the two compounds being dependent upon such factors as therelative proportion of the two hydrocarbons employed, the amount ofsulphuric acid present and the exact temperature which to some extentcontrols the rate and course of the reaction.

Similarly condensations between butylenes, amylenes or heptylenes andbenzol or its homologs may be produced with a minimum degree ofpolymerization occurring between the oleflnic hydrocarbons. Thecompounds thus produced between benzol and oleilns up to 5 carbon atomswherein one molecule of olefin condenses with one molecule of benzol,boil within the ordinary range of commercial motor fuels, say below 430F., and consequently their addition to any given gasoline to increaseits anti-knock quality causes very little change in the distillationcurve of the fuel. Condensation products which are of a higher boilingcharacter, are usually formed in such small amounts that they vaporizealong with the lower boiling hydrocarbons and cause no specialdlmculties in carburetion. Irformed in larger quantities they may beleft as residue in the redistillation of the products, either alone ormixed with gasoline.

The oleflns produced under the special conditions of crackingcharacteristic of the first step mixtures thereof) such as benzol,toluol, the

xylols, etc, and the compounds formed may then be utilized as blendingmaterial to increase the anti-knock value of gasolines which aredeilcient in this respect. In another mode of operaupon the mixture as awhole.

'tion which is of quite general utility, the highly oieflnic gasmixtures from the first step of the process may be reacted witharomatics previously blended with gasoline so that the anti-knockderivatives'oi mixed paramnlc-aroniatlc character are produced in situ.and any further redoing comprising limited sulphuric acid treatment,sweetening, steam distillation, etc.,-is conducted In still other casesthe oleflnic gas mixture may be reacted with hydrocarbons of an aromaticcharacter which are produced in the pyrolysis of naphthenic or mixedbase charging oils such as distillates or residua from California orTexas fields, there beingno need in certain oi these cases for theaddition of any large amount of aromatic hydrocarbons from outsidesources to furnish material to react with the oleiinic gases.

In practicing the first step of the process involving the pyrolysis ofhydrocarbon gas mintures under accurately controlled conditions attemperature, pressure and time any suitable type of apparatus may beemployed since the invention is not limited to any particularmodification oi plant design or type oi equipment. The materials used inheating elements employed in the first step will be determined to someextent by the temperatures employed, tubes of high chromium steel andother high melting alloys being utilized at the lower ranges while tubesof reiractory materials such as lire clay. silica, sllli manite; etc...are best employed at the higher temperatures which approach the fusingmint of iron.

The apparatus employed in the first step is I preferably designed topermit accurate control of time factor and in most cases the heatedreaction zone will consist of a tube oi relatively small capacitythroughwhich the gas mixture is drawn at an accurately controlled rate. Thetube may be heated by any suitable source oi heat such as ordinaryflames or hot combustion gases, or

electrical resistors may be used with due consideration of the costfactor involved. The gases may be preheated before passage through thereaction zone to some point under the critical conditions necessary forhest results, this preheating involving the H use of ordinary tubularheating elements heated by combustion gases, care being exercised,however, that the gas mixture is not brought too soon to'the temperaturer quired for the desired reactions. The process can he carried out byalternately heating a furnace consisting of stones with canalstherebetween and.

then passing the gas through the hot canals.

Alter passage through the main reaction zone;

the gas mixture is preferably quickly cooled so that the time factor isaccurately controlled and the decomposition reactions are stopped atapolnt corresponding to mammum production of desired product's.

In conducting the second step of the process,

first step nary pressures, the oleflnic constituents under theseconditions reacting with benzol to form homologs of benzene which are oihigh antilrnoclr value and suitable for use as blending material toincrease the lrnoclcrating of inferior or knocking gasollnes. a

In the second step of the process other refining treatment may bebrought about incidental to the main reactions of condensation .betweenoleline and aromatics when the reactions occur in gasolines containingundesirably large amounts or color and gum-forming compounds and highsulphur content such as, for example, gasolines from cracking highsulphur oils. In these cases, the acid treatment may serve. topolymerize diand tri-olefines to high boiling polymers readily removableby subsequent distillation and at the same time produce high anti-knockcompounds by the union of liquid mono oleiins and aromatic or cyclichydrocarbons according to the same general type of reaction which talresplace between the oleiins from the first step oi the process and thearomatic hydrocarbons.

in cases involving the alternate method of treating gasoline containingaromatics with olefinic gases, the use of the process in connection withthe improvement of such gasoline does not preclude the use of otherrefining treatments upon the gasoline either before or alter theproduction oi the condensation reactiom. Thus. for example, crackedgasolines may be treated by the use oi? sulphuric acid, neutralized,sweetened anclredistilled, after which aromatics from rately producedhave been added to the gasoline,

the blend may be further treated by'reagents adapted to remove color,gum and'sulphur and p the treated gasoline may be rerun it it is foundthat the best results are obtained by this type oi operation.

special equipment is seldom necessary; 7 the oral nary batchandcontinuous'"sulphuricfacidtrea ing plants common to'most petroleumrefineries being generally adaptable to use, if means'ar'e' provided formaintaining the necessary tempera tures. For exam'ple, a regulatedamount of cooled sulphuric acid of commercial grade may beadded,theagitation orcirculation of the benzol and 7' sulphuric acid the.olefinic gas mixtures from the may be passed therethrough at ordi- Anexample or the results obtainable by the use oi the process of theinvention may be given which involves in the first step the furtherprocessing of the cracking gas mixture shown in a preceding part of thespecification, the temperature employed being 950 (3., the pressure 59mm. of mercury absolute and the time factor 0.0075 second. Under theseconditions the percentage of acetylene in the gas mixture will bepractically 0, the percentage of ethylene approximately 20 and thepercentage of propylene and higher 'oleflnic homologs 15 to 20, theother constituents being chiefly paramn hydrocarbons which do not enterinto the condensation reactions.

The gas mixture produced in the first step may be conducted into agasoline blend consisting oi by'vclume of a straight run parafinic gas-4' I oline and 20% by volume of benzol, the octane number of the blendbeing Sulphuric acid in an amount equal to approximately 20 pounds perbarrel of the blend may be present and be maintained in suspension in afinely divided condition by means of mechanical stirring equipment orpump circulation during the admission of the olefinic gas mixture.preferably employed to prevent undue temperature rise and minimizeoxidation and polymerization reactions. The gas mixture may beintroduced at the rate of 10 to 15 cubic feet per hour per barrel ofblend and the treatment continued until the blend has increased 18% byweight, this weight increase corresponding to anincrease ofapproximately 14% by volume of the blend.

The acid layer may be separated and removed, and the treated gasolineneutralized and redistilled to the same end point which the blend hadprior to the gas treatment. there being recovered a finished gasolineequal to 110% by volume of the original blend. This gasoline may havethe properties shown in the following table:

Gravity A. P. I 56 End point "F 410 Color, Saybolt 30 Mg gum (copperdish method) 20 Octane number The advantages of the process are evidentfrom a consideration of the foregoing data which indicates that anoverall increase of 25 points in octane number was obtained by thecombination of steps comprising the process of the invention since thestraight run gasoline prior to theaddition of benzol and contacting withthe cracked gases was only 45%. Moreover, the overall yield apart fromthat obtained by the addition of benzol was increased 10%.

Neither specification nor example is to be construed in the light ofimpossing undue limitations upon the generally broad scope of theinvention.

Cooling coils are aoeasw I claim as my invention:

1. A process for increasing the anti-knock value of gasoline containinga hydrocarbon of the benzene series. which comprises adding sulphuricacid to the gasoline, passing oleflnic material in gaseous form into theresultant mixture, reacting the oleflnic material with said hydrocarbonin the presence of the acid to form an alkylated aromatic havinganti-knock properties, and separating the gasoline containing the thusformed aling the thus formed alkylated aromatic from the acid layer. I

3. A process for increasing the anti-knock value of gasoline containinga hydrocarbon of the benzene series, which comprises adding analkylating agent to the gasoline, passing oleflnic material in gaseousform into the resultant mixture, reacting the oleflnic material withsaid hydrocarbon in the presence of said agent to form an alkylatedaromatic having anti-knock properties, and separating the gasolinecontaining the thus formed alkylated aromatic from the alkylating agent.

4. A process for improving cracked gasoline containing, as a resultof'the cracking, a hydrocarbon of the benzene series, which comprisesadding an alkylating agent to the gasoline, passing oleflnic material ingaseous form into the resultant mixture, reacting the oleflnlc materialwith .said hydrocarbon in the presence of said agent to form analkylated aromatic having antiknock properties, and separating thegasoline containing the thus formed alkylated aromatic from thealkylating agent. 7 VLADIMIR IPA'I'IEFF.

